Billet Carbs

[machinedcomp]

I recently designed some 38 mm (1.500 Dia. Venturi) Billet carburetors. I have most of the Machining finished and will bench test very soon.
My original intent was to at least match the performance of the current Mikuni & Delorto's that I use. But the Flow bench numbers look very promising.
Here are some picture of the steps along the way.

[runabout333]

Just Curious,,, What alloy??.. I have worked 25 years for a laser shop,,, but the machne world intrigues me..
Do you have a wire EDM??? Wire EDM's here in the Dorothy and Toto land are very popular as we have a vast amount of
plastic extrusion and plastic injection shops in this area..

[machinedcomp]

I use 6061 T6 Aluminum for the carb body and black Acetal (plastic) for the rotary barrel. No I don't have any EDM machines, there isn't a lot of that type of work in my area. I have CNC mills & lathes.

[dwhitford]

Lee, are these carburetors to have rotary throttles in them like the Koenig carburetors of yore? What do you plan for float bowls? I like the low profile. Slide-throttle Miks & DelOrtos are tall and hard to mount in some applications.

[machinedcomp]

Yes these are a rotary barrel type carburetor. Very similar to the Konig/Konny motors. The main differences are. The barrel is mounted horizontally, so as it opens it exposes the first fuel circut at the bottom of the venturi. As it continues open it exposes the main emulsion tube. Since a pro engine operates at primarily 3/4 to wide open throttle, I'm only using two fuel circuts. This is a recirculating system. The lower line fills the fuel chamber and the upper line returns the excess fuel back to the tank. This is a common setup used in Shifter Karts. Commonly referred to as a pump around system. I'll use two fuel pumps to do this. So there are no floats or needle/seat assembly. I made the emulsion tube and the main jets all one piece. So jetting changes are made changing the I.D. of the emulsion tube. It can be done from the top side, without draining the fuel or taking the carb off.

[GarE-12]

How do we order?

[machinedcomp]

Not currently for sale. They look good on a flow bench but I want to have them well tested first.

[Steve77t]

Hi Lee, Please give me a call 770 490 7752 Steve

[Smitty]

Very interesting, Lee, especially your horizontal valves!!

I tried something roughly like this myself somewhere in the mid-'70s, three essentially Konig-style carbs starting from a chunk of 2"X2" 6061 chucked up in my little Craftsman lathe. 32mm bore was, I thought, about as big as could reasonably made from 2" bar stock. I made my valves of aluminum (some of Konig's were) but got around the stiction problem by coating the outside of the valves with Kal-Gard's heat-cured moly spray. Since my piece of bar-stock was only big enough to make the throttle bodies, I made separate float (-less) bowls, hung from rubber mounts. Made the overflow funnels of Delrin plastic. The little brass parts came from production carbs; I didn't try to make my own as you have, Lee. Anyway, I had not even finished the attach-points for the carb linkage when a motorcycle roadracer came over, saw what I was doing, and gave me too much money for the pair of carbs I was going to try on my old A Konig. Never heard from him again, possibly because his check was no good.

I still have the third carb stored with the rest of the old junk. Back then I took it to an SOA meeting to show off, and see what they thought about my using it on a 125, in combination with a second little Tillotson pumper, 32mm being small for 125. But they told me that the rules precluded a second carb in that class. Maybe that rule has changed now . . . .

[pav225]

Awesome work Lee.